I'm sorry, there was a critical issue with the Daily Challenge due to my mistake.
If your computer's time format was not yyyy/mm/dd, you were not able to participate in the daily challenge, or your daily challenge was different from others. This issue has now been fixed.
If you have encountered this issue before, you will no longer be able to find your previous ranking on the leaderboard of daily challenge after this update. But don't worry, I've just moved those wrong dates to a few months ago and you can still receive your rewards as normal according to your previous ranking. Only, just it will show the date as a few months ago.